plain text document attachment (lguest64-debug-utils.patch)
This patch contains some nice features used to debug the lguest64 guest.
It has a way to print page tables for either the host or the guest.
It incorporates kallsyms, and can do a nice back trace of a guest
when it crashes. The guest needs kallsyms obviously compiled in.
Note: This code needs to be fixed to be more secure!
Implements a lgdebug_print that can be used within the host that
will only print when lguest_debug is true. There's a hypercall
that the guest can call to turn this on.
There's also a function called lguest_set_debug(n) the makes it
easy for the guest to turn it on. Where n=1 will turn on debugging
prints, and n=0 will turn it off. (well n!=0 will turn it on).
Signed-off-by: Steven Rostedt <srostedt@xxxxxxxxxx>
Cc: Glauber de Oliveira Costa <glommer@xxxxxxxxx>
Cc: Chris Wright <chrisw@xxxxxxxxxxxx>
Index: work-pv/arch/x86_64/lguest/lguest_debug.c
===================================================================
--- /dev/null
+++ work-pv/arch/x86_64/lguest/lguest_debug.c
@@ -0,0 +1,532 @@
+/*
+ lguest debug utils. Modified from various other parts of Linux.
+ What was modified is Copyright 2007 Steven Rostedt, Red Hat
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+*/
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/freezer.h>
+#include <linux/kallsyms.h>
+#include <asm/paravirt.h>
+#include <asm/hv_vm.h>
+#include <asm/pgtable.h>
+#include <asm/uaccess.h>
+#include "lguest.h"
+
+int lguest_debug;
+
+static DEFINE_SPINLOCK(lgdebug_print_lock);
+#define LGDEBUG_BUF_SIZ 1024
+static char lgdebug_print_buf[LGDEBUG_BUF_SIZ];
+
+void lgdebug_vprint(const char *fmt, va_list ap)
+{
+ unsigned long flags;
+
+ if (!lguest_debug)
+ return;
+
+ spin_lock_irqsave(&lgdebug_print_lock, flags);
+ vsnprintf(lgdebug_print_buf, LGDEBUG_BUF_SIZ-1, fmt, ap);
+ printk("%s", lgdebug_print_buf);
+ spin_unlock_irqrestore(&lgdebug_print_lock, flags);
+}
+
+void lgdebug_print(const char *fmt, ...)
+{
+ va_list ap;
+
+ if (!lguest_debug)
+ return;
+
+ /* irq save? */
+ va_start(ap, fmt);
+ lgdebug_vprint(fmt, ap);
+ va_end(ap);
+}
+
+void lguest_dump_vcpu_regs(struct lguest_vcpu *vcpu)
+{
+ struct lguest_regs *regs = &vcpu->regs;
+
+ printk("Printing VCPU %d regs cr3: %016llx\n", vcpu->id, regs->cr3);
+ printk("RIP: %04llx: ", regs->cs & 0xffff);
+ lguest_print_address(vcpu, regs->rip);
+ printk("RSP: %04llx:%016llx EFLAGS: %08llx\n", regs->ss, regs->rsp,
+ regs->rflags);
+ printk("RAX: %016llx RBX: %016llx RCX: %016llx\n",
+ regs->rax, regs->rbx, regs->rcx);
+ printk("RDX: %016llx RSI: %016llx RDI: %016llx\n",
+ regs->rdx, regs->rsi, regs->rdi);
+ printk("RBP: %016llx R08: %016llx R09: %016llx\n",
+ regs->rbp, regs->r8, regs->r9);
+ printk("R10: %016llx R11: %016llx R12: %016llx\n",
+ regs->r10, regs->r11, regs->r12);
+ printk("R13: %016llx R14: %016llx R15: %016llx\n",
+ regs->r13, regs->r14, regs->r15);
+
+ printk("errcode: %llx trapnum: %llx\n",
+ regs->errcode, regs->trapnum);
+
+ lguest_dump_trace(vcpu, regs);
+}
+
+struct guest_ksym_stuff {
+ unsigned long *addresses;
+ unsigned long num_syms;
+ u8 *names;
+ u8 *token_table;
+ u16 *token_index;
+ unsigned long *markers;
+};
+
+static struct lguest_text_ptr *get_text_segs(struct lguest_vcpu *vcpu)
+{
+ struct lguest_guest_info *linfo = vcpu->guest;
+ struct lguest_text_ptr *segs, **p;
+ struct lguest_text_ptr *g;
+ unsigned long addr;
+ int i;
+
+ if (!linfo->lguest_data)
+ return NULL;
+
+ addr = lhread_u64(vcpu, (u64)&linfo->lguest_data->text);
+ if (!addr)
+ return NULL;
+
+ g = (struct lguest_text_ptr*)addr;
+
+ p = &segs;
+
+ /* only allow for 10 segs */
+ for (i=0; i < 10; i++) {
+ *p = kmalloc(sizeof(*segs), GFP_KERNEL);
+ if (!*p)
+ goto free_me;
+ (*p)->start = lhread_u64(vcpu, (u64)&g->start);
+ (*p)->end = lhread_u64(vcpu, (u64)&g->end);
+ addr = lhread_u64(vcpu, (u64)&g->next);
+ p = (struct lguest_text_ptr**)&((*p)->next);
+ if (!addr)
+ break;
+ g = (struct lguest_text_ptr*)addr;
+ }
+ *p = NULL;
+
+ return segs;
+
+free_me:
+ while (segs) {
+ g = (struct lguest_text_ptr*)segs->next;
+ kfree(segs);
+ segs = g;
+ }
+ return NULL;
+}
+
+static int is_text_seg(struct lguest_text_ptr *segs, unsigned long addr)
+{
+ while (segs) {
+ if (addr >= segs->start &&
+ addr <= segs->end)
+ return 1;
+ segs = (struct lguest_text_ptr*)segs->next;
+ }
+ return 0;
+}
+
+static void put_text_segs(struct lguest_text_ptr *segs)
+{
+ struct lguest_text_ptr *p;
+
+ while (segs) {
+ p = (struct lguest_text_ptr*)segs->next;
+ kfree(segs);
+ segs = p;
+ }
+}
+
+static unsigned int expand_symbol(struct lguest_vcpu *vcpu,
+ struct guest_ksym_stuff *kstuff,
+ unsigned int off, char *result)
+{
+ int len, skipped_first = 0;
+ const u8 *tptr, *data;
+
+ /* get the compressed symbol length from the first symbol byte */
+ data = &kstuff->names[off];
+
+ len = lhread_u8(vcpu, (u64)data);
+
+ data++;
+
+ /* update the offset to return the offset for the next symbol on
+ * the compressed stream */
+ off += len + 1;
+
+ /* for every byte on the compressed symbol data, copy the table
+ entry for that byte */
+ while(len) {
+ u8 idx;
+ u16 tok;
+ idx = lhread_u8(vcpu, (u64)data);
+ tok = lhread_u16(vcpu, (u64)(&kstuff->token_index[idx]));
+ tptr = &kstuff->token_table[ tok ];
+ data++;
+ len--;
+
+ idx = lhread_u8(vcpu, (u64)tptr);
+ while (idx) {
+ if(skipped_first) {
+ *result = idx;
+ result++;
+ } else
+ skipped_first = 1;
+ tptr++;
+ idx = lhread_u8(vcpu, (u64)tptr);
+ }
+ }
+
+ *result = '\0';
+
+ /* return to offset to the next symbol */
+ return off;
+}
+
+static unsigned long get_symbol_pos(struct lguest_vcpu *vcpu,
+ struct guest_ksym_stuff *kstuff,
+ unsigned long addr,
+ unsigned long *symbolsize,
+ unsigned long *offset)
+{
+ unsigned long symbol_start = 0, symbol_end = 0;
+ unsigned long i, low, high, mid;
+
+ /* do a binary search on the sorted kallsyms_addresses array */
+ low = 0;
+ high = kstuff->num_syms;
+
+ while (high - low > 1) {
+ mid = (low + high) / 2;
+ if (kstuff->addresses[mid] <= addr)
+ low = mid;
+ else
+ high = mid;
+ }
+
+ /*
+ * search for the first aliased symbol. Aliased
+ * symbols are symbols with the same address
+ */
+ while (low && kstuff->addresses[low-1] == kstuff->addresses[low])
+ --low;
+
+ symbol_start = kstuff->addresses[low];
+
+ /* Search for next non-aliased symbol */
+ for (i = low + 1; i < kstuff->num_syms; i++) {
+ if (kstuff->addresses[i] > symbol_start) {
+ symbol_end = kstuff->addresses[i];
+ break;
+ }
+ }
+
+ /* if we found no next symbol, we use the end of the section */
+ if (!symbol_end) {
+ return (unsigned long)(-1UL);
+#if 0
+ if (is_kernel_inittext(addr))
+ symbol_end = (unsigned long)_einittext;
+ else if (all_var)
+ symbol_end = (unsigned long)_end;
+ else
+ symbol_end = (unsigned long)_etext;
+#endif
+ }
+
+ *symbolsize = symbol_end - symbol_start;
+ *offset = addr - symbol_start;
+
+ return low;
+}
+
+static int is_ksym_addr(struct lguest_guest_info *linfo,
+ unsigned long addr)
+{
+ /* need to look up the segs */
+ return 1;
+}
+
+static unsigned int get_symbol_offset(struct lguest_vcpu *vcpu,
+ struct guest_ksym_stuff *kstuff,
+ unsigned long pos)
+{
+ const u8 *name;
+ int i;
+ unsigned long idx;
+
+ idx = lhread_u64(vcpu, (u64)&kstuff->markers[pos>>8]);
+
+ /* use the closest marker we have. We have markers every 256 positions,
+ * so that should be close enough */
+ name = &kstuff->names[ idx ];
+
+ /* sequentially scan all the symbols up to the point we're searching for.
+ * Every symbol is stored in a [<len>][<len> bytes of data] format, so we
+ * just need to add the len to the current pointer for every symbol we
+ * wish to skip */
+ for(i = 0; i < (pos&0xFF); i++) {
+ u8 c;
+ c = lhread_u8(vcpu, (u64)name);
+ name = name + c + 1;
+ }
+
+ return name - kstuff->names;
+}
+
+static const char *lguest_syms_lookup(struct lguest_vcpu *vcpu,
+ unsigned long addr,
+ unsigned long *symbolsize,
+ unsigned long *offset,
+ char **modname, char *namebuf)
+{
+ struct lguest_guest_info *linfo = vcpu->guest;
+ struct lguest_data *data = linfo->lguest_data;
+ struct guest_ksym_stuff kstuff;
+ const char *msym;
+ unsigned long *ptr;
+ int i;
+
+ kstuff.addresses = (unsigned long*)lhread_u64(vcpu, (u64)&data->kallsyms_addresses);
+ kstuff.num_syms = lhread_u64(vcpu, (u64)&data->kallsyms_num_syms);
+ kstuff.names = (u8*)lhread_u64(vcpu, (u64)&data->kallsyms_names);
+ kstuff.token_table = (u8*)lhread_u64(vcpu, (u64)&data->kallsyms_token_table);
+ kstuff.token_index = (u16*)lhread_u64(vcpu, (u64)&data->kallsyms_token_index);
+ kstuff.markers = (unsigned long*)lhread_u64(vcpu, (u64)&data->kallsyms_markers);
+
+ if (!kstuff.addresses || !kstuff.num_syms || !kstuff.names ||
+ !kstuff.token_table || !kstuff.token_index || !kstuff.markers)
+ return NULL;
+
+ /* FIXME: Validate all the kstuff here!! */
+
+ ptr = kmalloc(sizeof(unsigned long)*kstuff.num_syms, GFP_KERNEL);
+ if (!ptr)
+ return NULL;
+
+ for (i=0; i < kstuff.num_syms; i++) {
+ /* FIXME: do this better! */
+ ptr[i] = lhread_u64(vcpu, (u64)&kstuff.addresses[i]);
+ if (i && ptr[i] < ptr[i-1]) {
+ kill_guest(linfo, "bad kallsyms table\n");
+ kstuff.addresses = ptr;
+ goto out;
+ }
+ }
+ kstuff.addresses = ptr;
+
+ namebuf[KSYM_NAME_LEN] = 0;
+ namebuf[0] = 0;
+
+ if (is_ksym_addr(linfo, addr)) {
+ unsigned long pos;
+
+ pos = get_symbol_pos(vcpu, &kstuff, addr, symbolsize, offset);
+ if (pos == (unsigned long)(-1UL))
+ goto out;
+
+ /* Grab name */
+ expand_symbol(vcpu, &kstuff,
+ get_symbol_offset(vcpu, &kstuff, pos), namebuf);
+ *modname = NULL;
+ kfree(kstuff.addresses);
+ return namebuf;
+ }
+
+ /* see if it's in a module */
+ msym = module_address_lookup(addr, symbolsize, offset, modname);
+ if (msym) {
+ kfree(kstuff.addresses);
+ return strncpy(namebuf, msym, KSYM_NAME_LEN);
+ }
+
+out:
+ kfree(kstuff.addresses);
+ return NULL;
+}
+
+void lguest_print_address(struct lguest_vcpu *vcpu, unsigned long address)
+{
+ unsigned long offset = 0, symsize;
+ const char *symname;
+ char *modname;
+ char *delim = ":";
+ char namebuf[KSYM_NAME_LEN+1];
+
+ symname = lguest_syms_lookup(vcpu, address, &symsize, &offset,
+ &modname, namebuf);
+ if (!symname) {
+ printk(" [<%016lx>]\n", address);
+ return;
+ }
+ if (!modname)
+ modname = delim = "";
+ printk(" [<%016lx>] %s%s%s%s+0x%lx/0x%lx\n",
+ address, delim, modname, delim, symname, offset, symsize);
+
+}
+
+void lguest_dump_trace(struct lguest_vcpu *vcpu, struct lguest_regs *regs)
+{
+ unsigned long stack = regs->rsp;
+ unsigned long stack_end = (regs->rsp & PAGE_MASK) + PAGE_SIZE;
+ unsigned long start_kernel_map;
+ unsigned long page_offset;
+ unsigned long addr;
+ struct lguest_text_ptr *segs;
+
+ printk("Stack Dump:\n");
+ start_kernel_map = vcpu->guest->start_kernel_map;
+ page_offset = vcpu->guest->page_offset;
+
+ segs = get_text_segs(vcpu);
+ if (!segs)
+ return;
+
+ for (; stack < stack_end; stack += sizeof(stack)) {
+ addr = lhread_u64(vcpu, guest_pa(vcpu->guest, stack));
+ if (is_text_seg(segs, addr)) {
+ lguest_print_address(vcpu, addr);
+ }
+ }
+
+ put_text_segs(segs);
+}
+
+static u64 read_page(struct lguest_vcpu *vcpu, u64 page, u64 idx)
+{
+ u64 *ptr;
+
+ if (!vcpu) {
+ ptr = __va(page);
+ return ptr[idx];
+ }
+
+ return lhread_u64(vcpu, page+idx*sizeof(u64));
+}
+
+static void print_pte(u64 pte, u64 pgd_idx, u64 pud_idx, u64 pmd_idx, u64 pte_idx)
+{
+ printk(" %3llx: %llx\n", pte_idx, pte);
+ printk (" (%llx)\n",
+ ((pgd_idx&(1<<8)?(-1ULL):0ULL)<<48) |
+ (pgd_idx<<PGDIR_SHIFT) |
+ (pud_idx<<PUD_SHIFT) |
+ (pmd_idx<<PMD_SHIFT) |
+ (pte_idx<<PAGE_SHIFT));
+}
+
+static void print_pmd(struct lguest_vcpu *vcpu,
+ u64 pmd, u64 pgd_idx, u64 pud_idx, u64 pmd_idx)
+{
+ u64 pte;
+ u64 ptr;
+ u64 i;
+
+ printk(" %3llx: %llx\n", pmd_idx, pmd);
+
+ /* 2M page? */
+ if (pmd & (1<<7)) {
+ printk (" (%llx)\n",
+ ((pgd_idx&(1<<8)?(-1ULL):0ULL)<<48) |
+ (pgd_idx<<PGDIR_SHIFT) |
+ (pud_idx<<PUD_SHIFT) |
+ (pmd_idx<<PMD_SHIFT));
+ } else {
+ pte = pmd & ~(0xfff) & ~(1UL << 63);
+ for (i=0; i < PTRS_PER_PTE; i++) {
+ ptr = read_page(vcpu, pte, i);
+ if (ptr)
+ print_pte(ptr, pgd_idx, pud_idx, pmd_idx, i);
+ }
+ }
+}
+
+static void print_pud(struct lguest_vcpu *vcpu,
+ u64 pud, u64 pgd_idx, u64 pud_idx)
+{
+ u64 pmd;
+ u64 ptr;
+ u64 i;
+
+ printk(" %3llx: %llx\n", pud_idx, pud);
+
+ pmd = pud & ~(0xfff) & ~(1UL << 63);
+ for (i=0; i < PTRS_PER_PMD; i++) {
+ ptr = read_page(vcpu, pmd, i);
+ if (ptr)
+ print_pmd(vcpu, ptr, pgd_idx, pud_idx, i);
+ }
+}
+
+static void print_pgd(struct lguest_vcpu *vcpu,
+ u64 pgd, u64 pgd_idx)
+{
+ u64 pud;
+ u64 ptr;
+ u64 i;
+
+ printk(" %3llx: %llx\n", pgd_idx, pgd);
+ pud = pgd & ~(0xfff) & ~(1UL << 63);
+ for (i=0; i < PTRS_PER_PUD; i++) {
+ ptr = read_page(vcpu, pud, i);
+ if (ptr)
+ print_pud(vcpu, ptr, pgd_idx, i);
+ }
+
+}
+
+static void print_page_tables(struct lguest_vcpu *vcpu,
+ u64 cr3)
+{
+ u64 pgd;
+ u64 ptr;
+ u64 i;
+
+ printk("cr3: %016llx\n", cr3);
+ pgd = cr3;
+
+ for (i=0; i < PTRS_PER_PGD; i++) {
+ ptr = read_page(vcpu, pgd, i);
+ if (ptr)
+ print_pgd(vcpu, ptr, i);
+ }
+}
+
+void lguest_print_page_tables(u64 *cr3)
+{
+ if (!cr3) {
+ printk("NULL cr3 pointer????\n");
+ return;
+ }
+ print_page_tables(NULL, __pa(cr3));
+}
+
+void lguest_print_guest_page_tables(struct lguest_vcpu *vcpu, u64 cr3)
+{
+ print_page_tables(vcpu, cr3);
+}
--
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